Measuring the Kelvin-Helmholtz instability, stabilized by a tangential magnetic field

Abstract In a flow channel we experimentally investigate the stability of the interface between a laminar flow of diamagnetic fluid, superimposed by a resting layer of ferrofluid. This interface is locally perturbed by means of a bar oscillating with a driving frequency. Measuring the growth rate of the interfacial waves, we explore the stabilizing effect of a homogeneous magnetic field oriented in flow direction. A zero growth rate determines the critical flow velocity. The latter increases with the applied magnetic field and depends sensitively on the driving frequency. The results are described in part by an established, simple inviscid model.